The Algebraist (690 pages, Orbit 2005 edition; ISBN:1-84149-230-2) is
a science fiction novel by british author Iain M. Banks. The background is a
typical "space opera" setting, with lots of sentient species,
apart from Humans, all living in a very complex galactic society.António Martins, 29 December 2005

One of the alien races in this novel are the Dwellers, an enigmatic
hydrogen breathing species who dwells in gas giants. These form a very ancient
Galaxy-spanning civilization and engage in many forms of apparently
inconsequential amusement, some of which include the use of crafts which
"sail" three-dimentionally in gas giant atmospheric volumes flows
with magnetic fields for wind. These are mentioned for having flags of some
sort. On page 393, refering to generic Gas Clipper vessel design and attire: